We propose to use recombinant DNA technology to exchange several putative functional domains between human factor IX, X and VII. These domains include, the "gla" region, exon C, the epidermal growth factor regions and the heavy chain and first 40 amino acids of the heavy chain. Each construction will be expressed in a transient expression system in the cos cell line. These altered factor IX molecules will all have the factor IX activation peptide. A monoclonal antibody specific for the threonine dimorphic form of the factor IX molecule (and which does not react with bovine factor IX) will be used to purify the proteins produced from the recombinant constructions. Each purified altered factor IX molecule will be assayed for its ability to function in coagulation in the one stage assay in the throboplastin time. The molecules will also be tested to determine if they can be activated, if they bind normally to factor VIII (or bind to the cofactor for factor X or VII) and tested to determine if they bind to endothelial cells.